1. Field of the Invention
The present invention relates to a method of processing speech, especially for hearing-impaired listeners or the elderly.
2. Description of the Related Art
It has been quite a long time since hearing aids were first developed. The main concept of the hearing aid is to amplify a sound so as to help a hearing-impaired listener to hear a previously-unheard sound, and to make the sound amplification process hardly generate a sound delay. Furthermore, if the hearing aid is focused on processing the frequency, generally it is to reduce the sound frequency. For example, U.S. Pat. No. 6,577,739 discloses an “Apparatus and methods for proportional audio compression and frequency shifting” to compress a sound signal according to a specific proportion for being provided to a hearing-impaired listener with hearing loss in a specific frequency range. However, this technique involves compressing the overall sound; even though it can perform real-time output, it can result in serious sound distortion.
U.S. Pat. No. 4,454,609 discloses a method of “Speech intelligibility enhancement” used for enhancing the consonant sounds of speech with high frequency. The greater the high frequency content relative to the low, the more such high frequency content is boosted. In this known prior art, consonant high frequency sounds are enhanced. However, it is very difficult to detect the occurrence of consonants in daily conversations. Therefore, this known prior art is not applicable to a hearing aid.
U.S. Patent Publication No. 2007/0127748 discloses a method of “Sound enhancement for hearing-impaired listeners” to process high frequency sound segments into low frequency sound segments. However, this known prior art neither discloses how to process the low frequency sound segments nor determines whether to divide the vowels and consonants for performing sound processing.
Therefore, there is a need to provide a method of processing a voice segment and a hearing aid capable of processing speech in real time and simplifying the calculations of the process, thereby enhancing the sound accuracy heard by a hearing-impaired listener to mitigate and/or obviate the aforementioned problems.